Editing User Permissions?

Hi, I was wondering if there is anyway for me to edit a users ability to edit files which were made before her account was made? I have looked around and can’t find a way to edit that anywhere, I want to let her be able to edit files under my domain, but I would like her to have her own username and not have to use mine.


It’s a Group permission trick. Oh, and she’ll have to use SFTP (or SSH).